Vented accelerating pump



J1me 1960 A. w. ZUB 2,942,861

vzm'szn ACCELERATING PUMP Filed Nev. 3, 1958 2 Sheets-Sheet 1 F l G. l

F I G. 2 29 INVENTOR.

ALBERT W. ZUB

ATTORNEY June 28, 1960 A. w. ZUB 2,942,861

VENTED ACCELERATING PUMP Filed Nov. 3, 195a 2 Sheets-Sheet 2 6 INVENTOR.

ALBERT w. ZUB w ATTORNEY 2,942,861 VENTED ACCELERATHWG PUMP Albert W. Zn'b, St. Louis, Mo., assignor to ACF Industries, Incorporated, New York, N.Y., a corporation of New Jersey Filed Nov. 3, 195a, Ser. No. 771,304

8 Claims. (Cl. 261-34) This invention relates to pumps, and more particularly to accelerating pumps such as are used in carburetors for automotive engines.

It will be understood that a carburetor for an automotive engine may .be provided with an accelerating pump for pumping fuel into the mixture conduit of the carburetor when the throttle of the carburetor is opened. Such a pump usually comprises a generally vertical pump cylinder and a pump plunger slidable in the cylinder, the plunger being controlled by the throttle of the carburetor in such manner that when the throttle is opened, the plungeris driven downward through a discharge stroke to force-feed fuel into the mixture conduit, and as the throttle is closed, the plunger is returned upward through an intake stroke to draw in fuel from the fuel bowl of the carburetor. It is desirable that such a pump be so constructed as to be capable of venting fuel vapor such as may collect in the lower end. of the pump cylinder each time the plunger is returned, and it is an object of this invention to provide an economical, reliable construction for this purpose which,

while assuring venting on each return stroke of theplunger, provides a tight seal against leakage-of fuel past the plunger on discharge strokes. A feature of the invention is that a single member is made to serve both as a packing member for sealing purposes and as a valve member for fuel vapor venting purposes, the valve function of this member being realized'simply in response to reciprocation of the plunger. in general, the plunger comprises a rod which is provided with spaced upper and lower heads. Slidable on the rod between these headsis a special packing member made of flexible resilient material of inverted cup shape having a top wall provided with a central opening slidably receiving the portion of the rod between the heads and having an annular depending skirt in slidingsealing engagement with the internal-surface of the cylinder. The heads are spaced a distance greater than the thickness of the top wall of the packing member, and the pack-- ing member axially slidable on the rod between a raised position relative to the rod engaging the upper head and a lower position relative to the rod engaging the lower head. The top wall has a vent hole located radially outward from its central opening. 'The arrangement is such that when the rod moves upward through an intake stroke, the .packing member slides down to its lower position or its central portion is pulled up, there. by opening up the vent hole to vent fuel vapor from the lower end portionof the cylinder. This action occurs because of friction between the skirt and the internal surface of the cylinder. When the rod is driven downward through a discharge stroke, the packing member assumes its upper position in which the vent hole therein is closed by the upper head, thereby sealing against escape of fuel past the plunger. Additionally, the rod may be provided with a passage extending up ward from its lower "end and a lateral port opening from this passage to the space between the heads, with the arrangement such that when the packing member is in its lowered position, the port is opened up to the space above the top wall of the packing member for venting fuel vapor from the lower end portion of the cylinder. Other objects and features will be in part apparent and in part pointed out hereinafter.

The invention accordingly comprises the constructions hereinafter described, the scope of the invention being indicated in the following claims.

In the accompanying drawings, in which one of various possible embodiments of'the invention is illustrated,.

Fig. 1 is a plan view of the carburetor, with parts broken away and shown in section;

Fig. 2 is a left side elevation of Fig. l, with parts broken away and shown in section;

Fig. 3 is a right side elevation of Fig. 1, with parts broken away and shown in section;

Fig. 4 is a plan view of the packing member per se; Fig. 5 is a vertical section taken on line 5-5 of Fig. 4; Fig. 6 is an enlarged vertical section taken on line 6-6 of Fig. 3;

Fig. 7 is a section corresponding to Fig. 6 showing a moved position of parts; and

Fig. 8 is a plan view of a lower washer or head per se. Corresponding reference characters indicate corresponding parts throughout the several views 'of the drawings.

Referring now to the drawings for a better understanding of the invention, the carburetor. has a fuel bowl section 19 above which is an air horn section 20 and be low which is a throttle body section 21 (see Figs. 2 and 3).

bowl 25 and an accelerating pump'cylinder 27 in the fuel bowl adjacent one end of the fuel bowl. 'It will the carburetor carrying the usual throttle valves 37 for the mixture conduits. At 39 is indicated the choke valve: for the carburetor, and at 41 is indicated the usual automatic choke control. p V

A plunger 43 'isreciprocable in the accelerating pump cylinder27. The cylinder 27 is adapted to be primed with fuel from the bowl 25 through an'intake slot 45 in the cylinder when the plunger moves upward through an intake stroke. Fuel is discharged by the plunger on a downward discharge stroke thereof from the lower end of the cylinder through a discharge passage 49 which leads to a jet cluster 51 (see Fig. 1) discharging into the mixture conduits 17. A discharge check valve 53 is provided adapted to open for flow of fuel through passage 49 on a discharge stroke.

The plunger. 43 comprises a cylindrical rod 55 extend-" ing down into the pump cylinder 27 from the air horn section 20 through a hole 57 in the bottom of the latter (see Fig. 3).

stitutes an upper head on the rod 55. Its diameter is appreciably less than the internal diameter of the pump cylinder 27. Another flat metal washer 67 of somewhat An air filter 23 is mounted on the air horn section. The fuel bowl section 19 is formed to provide a fuel' Adjacent its lower end the rod 55 formed with an'enlarged cylindrical portion 59 which] provides an upwardly facing shoulder 61 and a downwardly facing shoulder 63 (see Figs. 6 and 7). A flat metal washer 65 is provided on the rod 55 bearing. on the upwardly facing shoulder 61. This washer 65 con- I upper washer or head 67.

67 is provided with .anxannular series of arcuate slots; 81 ,(see .Eig.,8)j with which the vent holes 79 register smaller diameter than Washer 65 is provided on the ant 1'67. This packing member 71 (shown per se' in I Figs. and 5) is made of a flexible resilient elastorneric material in the form of an'inverted cup, having a sub-.

stantially flat circular "top wall 73 and annular skirt portion 75 of downwardly flaring conical forrnfThe top wall 73 is provided with a central hole 77 shown as from the lower end of the v shown in Fig. 6. This opens up the vent holes 79 for venting fuel vapor from the lower end. portion of the cylinder via slots 81 in washer 67 and holes 79 in top wall 73 and around the edge of the upper washer 65. Fuel vapor is also vented via the passage83 and the lateral ports 85 to the'space between the washers 65 and a square hole, the cylindrical enlarged'portion 59 of the rod '55 being freely slidably. received in the hole 77. The packing member is preferably formed from sheet material composed of polymerized tetrafiuoroethylene such as is sold under the trade designation'Tefion, having athickness less than spacing of the washers'or heads 65 and 67 (the height of the enlarged portion 59 of the rod 55). The sheet material is formed to the cup-shape shown in Fig. 5. The packing member is mounted Qon the enlarged portion 59 of the rod '55 with its annular I skirt portion 75 extending downward surrounding the lower washer or head 67. The dimensions of the packing member are such that the skirt 75. has a sliding sealing fit in the cylinder 27. The packing member being made of the polymerized 'tetrafluoroethylene material, the

. skirt tends to return-to flat condition so .asto hug the internal surface of cylinder 27 to provide a fuel-tight seal. 2 V 1 The top wall 7310f the packing member 71 is provided with vent holes 79, four such holes being shown,

located radially outward from its square center hole 77.

' Thetop wall 73 of the packing member 71 is slidable on .the enlarged-portion 5910f the'rod 55between the relatively raised position in which it is shown in' Fig. 7 in flatwise engagement with the upper washer or head 65 and the lowered position in which his shown in Fig.

67, and thence arpund the edge of the upper washer 65. If it should happen that the central portion of the top wall 73 of the packingmember should tend to cling to the enlarged portion 59 of the rod and thereby held from readily sliding down to its lower position of Fig. 6, the central portion of the top wall 73 be pulled up relative'to its margin to open up the vent holes 79 for venting fuel vapor from the lower end portion of the cylinder.

The material of which the packing member is composed, while being flexible and resilient, is sufiiciently rigid to be form-retaining and does not require any auxiliary support. Accordingly, the combined sealing and vent valve action is attained with relatively few parts, and these parts are easily assembled, making for an economical construction.

In view of the above, it be seen that the several objects of the invention fare achieved and other advantageous results attained. I Y j As various changes could be made in the above constructionswithout departing from thescope of the invention, .it is intended that all matter contained in theahove 6'in flatwise engagement with the lower washer or head 67. In the raised position, holes 79 areclosed by the The lower washertor head when the top wall 73 is in the lowered position; The

rod has an axial. passage .83' extending :up from lowenend and transverse holes traversing :its enlarged portion 59 .andintersecting passage ,83 providing lateral ports :85 opening from passage 83 to. the space :between the washers or heads and 67.

of the spring 87' when, the. throttle valves are opened by meau 'nf a linkagesueh as. shown inv Fig. .3 including an arm 89 on the thnottle shaft, alink 91 connecting arm 91mm arm9 cnashaft .9 area link 97 connecting another-arm 99 on shaft 95 to the upper end of the 1 i5i1 2;

an th thrptt e a v s 312:5;opn d. wun duti sis wise as iew d i F L ak9 i mbe =t 1 wi imm 2 25 .qlqskw se s v e n igdrives t un e 43 iipw ardes i sd b h r ra bis" m m e 71 d sui e i ises o t en s w in'FigJ 7 which its top wall 73 is in engagement with 'ilpper washer' or 'head ;65. Under these cir cu nstances the vent holes 79 in the top wall-73iof the pack- 7.

arej closed, and the plunger actsto force fuel description o sho n n t a wm a drawin Shall be interpreted as illustrative and not in a limiting sense.

I claim: 1

1. In a carburetor having a mixture conduit, a fuel bowl, a generally vertical accelerating pump cylinder, a fuel intake for admission of fuel from the bowl to the cylinder, a cheek-valved fuel discharge passage leading from the lower end portion of the pump cylinder to the mixture conduigand a pump plunger vertically reciprocable in the pump cylinder, said plunger comprising a rod, spaced upper and lower heads on the rod, a packing member made of flexible resilientmaterial of inverted cup shape having a top wall provided with a central opening slidably receiving the portion of the rod between said heads and having an annular depending skirt in sliding sealing engagement'with the internal'surfac'e of said pump cylinder, said heads being spaced a distance greater than the thickness of said top wall of said packing member and said' packing member being axially slidable on the rod between a raised position relative to the rod engaging the upper headand a lowered position relative to the rod engaging the lower head, and said top wall hav- 'ing a vent hole locatedradially outward from its central opening adapted when said packingmember is in lowered position to vent fuelivapor from the lowerend portion fuel intake for admission offuel frorn'the bowl to. the

cylinder, a check-valved fuel discharge passage leading from the lower end'portion of the pump cylinder to the miiit w 'wndli t a d ra p u ge 'yer is l r s nrocable in the pump cylinder, said plunger comprising a rod, spaced upper and lower heads on the rod adjacent its lower end, said heads being of smaller diameter than the internal diameter of said cylinder, said rod having a passage extending up from its lower end and a lateral port opening therefrom to the space between the heads, a packing member made of flexible resilient material of inverted cup shape having a normally substantially flat top wall provided with a central opening slidably receiving the portion of the rod between said heads and having an annular depending skirt extending downward surrounding the lower head in sliding sealing engagement with the internal surface of said pump cylinder, said heads being spaced a distance greater than the thickness of said top wall of said packing member and said packing member being axially slidable on the rod between a raised position relative to the rod engaging the upper head and a lowered position relative to the rod engaging the lower head wherein said port is open to the space above said top wall for venting fuel vapor from the lower end portion of the cylinder, and said top wall having a vent hole located radially outward from its central opening adapted either when said packing member is in lowered position or when the central portion of said top wall is pulled up relative to the margin of the top wall to vent fuel vapor from the lower end portion of the cylinder, and said vent hole being closed by the upper head when the packing member is in its raised position.

4. In a carburetor as set forth in claim 3, said packing member being formed of polymerized tetrafluoroethylene sheet material and the skirt thereof thereby having a tendency to return to flat condition so as to hug the internal surface of the pump cylinder.

5. In a carburetor having a mixture conduit, a fuel bowl, a generally vertical accelerating pump cylinder, a fuel intake for admission of fuel from the bowl to the cylinder, a check-valved fuel discharge passage leading from the lower end portion of the pump cylinder to the mixture conduit, and a pump plunger vertically reciprocable in the pump cylinder, said plunger comprising a rod, said rod having an enlarged portion adjacent its lower end providing an upwardly facing shoulder and a downwardly facing shoulder, an upper washer held on the rod engaging the upwardly facing shoulder, a lower washer held on the rod engaging the downwardly facing shoulder, said washers being of smaller diameter than the internal diameter of said cylinder, said rod having a passage extending up from its lower end and a lateral port opening therefrom to the space between the washers, a packing member made of flexible resilient material of inverted cup shape having a normally substantially flat top wall provided with a central opening slidably receiving said enlarged portion of the rod and having an annular depending skirt extending downward surrounding the lower washer in sliding sealing engagement with the internal surface of said pump cylinder, said washers being spaced a distance greater than the thickness of said top wall of said packing member and said packing member being axially slidable on said enlarged portion of the rod between a raised position relative to the rod engaging the upper washer and a lowered position relative to the rod engaging the lower washer wherein said port is open to the space above said top wall for venting fuel vapor from the lower end portion of the cylinder, and said top wall having a vent hole located radially outward from its central opening adapted either when said packing member is in lowered position or when the central portion of said top wall is pulled up relative to the margin of the top wall to vent fuel vapor from the lower end portion of the cylinder, and said vent hole being closed by the upper washer when the packing member is in its raised position.

6. In a carburetor comprising a body, a mixture conduit in said body, a throttle valve in said mixture conduit, a fuel bowl in said body, a generally vertical accelerating pump cylinder in said body, a fuel intake for admission and a pump plunger extending down through the top.

of fuel from the bowl to the cylinder, ta check-valved fuel; discharge passage in said body leading from the lower end portion of the pump cylinder to the mixture conduit,

of the body vertically reciprocable in the pump cylinder,

said plunger comprising a rod, means connecting said" throttle valve and rod for driving the rod downward on. opening the throttle valve and upward on closing the throttle valve, said rod having an enlarged portion, adjacent its lower end providing an upwardly facing shoulder and a downwardly facing shoulder, an upper washer on the rod engaging the upwardly facing shoulder, a spring reacting from the top of the body engaging said upper washer, a lower washer held on the rod engaging the downwardly facing shoulder, a packing member made of flexible resilient material of inverted cup shape having a top wall provided with a central opening slidably receiving said enlarged portion of the rod and having an annular depending skirt in sliding sealing engagement with the internal surface of said pump cylinder, said washers being spaced a distance greater than the thickness of said top wall of said packing member and said packing member being axially slidable on said enlarged portion of the rod between a raised position relative to the rod engaging the upper washer and a lowered position relative to the rod engaging the lower washer, and said top wall having a vent hole located radially outward from its central opening adapted when said packing member is in lowered position or when the central portion of said top wall is pulled up relative to the margin of the top wall to vent fuel vapor from the lower end of the cylinder, and said vent hole being closed by the upper washer when the packing member is in its raised position.

7. In a carburetor comprising a body, amixture conduit in said body, a throttle valve in said mixture conduit, a fuel bowl in said body, a generally vertical accelerating pump cylinder in said body, a fuel intake for admission of fuel from the bowl to the cylinder, a check-valved fuel discharge passage in said body leading from the lower end portion of the pump cylinder to the mixture conduit, and a pump plunger extending, down through the top of the body vertically reciprocable in the pump cylinder, said plunger comprising a rod, means connecting said throttle valve and rod for driving the rod downward on opening the throttle valve and upward on closing the throttle valve, said rod having an enlarged portion adjacent its lower end providing an upwardly facing shoulder and a downwardly facing shoulder, an upper washer on the rod engaging the upwardly facing shoulder, a spring reacting from the top of the body engaging said upper washer, a lower washer held on the rod engaging the downwardly facing shoulder, said washers being of smaller diameter than the internal diameter of said cylinder, said rod having a passage extending up from its lower end and a lateral port opening therefrom to the space between the washers, a packing member made of flexible resilient material of inverted cup shape having a normally substantially flat top wall provided with-a central opening slidably receiving said enlarged portion of the rod and having an annular depending skirt extending downward surrounding the lower washer in sliding sealing engagement with the internal surface of said pump cylinder, said washers being spaced a distance greater than the thickness of said top wall of said packing member and said packing member being axially slidable on said enlarged porton of the rod between a raised position relative to the rod engaging the upper washer and a lowered position relative to the rod engaging the lower washer wherein said port is open to the space above said top wall for venting fuel from the lower end portion of the cylinder, and said top wall having a vent hole located radially outward from its central opening adapted either when said packing member is in lowered position or when the central portion of said top wall is pulled up relative to the margin of the top wall to vent fuel vapor from the lower end portion of the cylinder, and

s a id vent hole being closed by thelupper washer when the packing member is in its raised position.

' A g ilmp pi i n er" u i Pu cylinder mp i 3". '9d j 'i avi a e P Q L-a i cent o'n'e end providing oppositely facing shoulders, a pair of'spaced-washers held on "the red engaging ihe shoulc le ijfa packing member made of flexibleje's'ilient material of eup shape having a Cir'eular wall provided with ya central nening slidably teeeiving' said enlarged portion of the fed and having an annular skirt f0; sliding sealing engagement with the internal surface of thepnn ip cylinder, said washers being spaced a distance greatenthzui the thickness of said wall of said packing member and 7 said packing member being axially slidable on said en larged portion of the rod between a first position relativ e' t o the rdid engaging pne washer and a second pesitidn relative to therdd ngagiflgih othef washer, and said wall having aha-1e lncated'radia'llyr outward ffoin its central opening adapted when 'saidfp-a'cking meinbefris in it's" second position to provide a vent, said hole being closed 

